This invention relates to a particulate material collecting apparatus.
Cyclones have hitherto been most popular as particulate material collecting apparatus. In cyclones, two types of vortical flows, i.e. forced vortical flow and semi-free vortical flow are formed, and the two types of vortical flows interfere with each other to cause a loss in pressure. To minimize mutual interference of the two types of vortical flows for reducing pressure loss requires an increase in the size of the apparatus which entails an increase in capital and operating cost.